AS A SURGICAL DRESSING 301 



upon a large artery, it seems very important that it should not shrink awav 

 from the sides of the vessel, but remain there, in its original dimensions, to serve 

 its purpose of a plug. 



On the same occasion on which I obtained this blood, I received a portion 

 into another vessel, and stirred it during coagulation to remove the fibrine. 

 This whipped blood answered my purpose perfectly, because, by virtue of the 

 remarkable tendency that the red corpuscles of the horse's blood have to aggregate 

 into dense masses, and so fall rapidly in the course of a short time, the mixture 

 of serum and red corpuscles was found, in three hours, to consist of about one- 

 half corpuscles and one-half serum, and therefore I could use the serum for 

 the purpose of my experiment. 



The experiment was performed in the following manner. A glass tube, 

 such as this (three-quarters of an inch in calibre and three inches in length), 

 open at each end, was packed with a certain weight of antiseptic dressing to be 

 tested, say sublimate-wool, occupying about two inches of the tube ; then 

 a weighed quantity of serum, just enough to soak the wool, was poured in at 

 one end of the tube held vertically ; it was then left for about half-an-hour 

 in a warm box at the temperature of the body, after being put into a stoppered 

 bottle, to prevent evaporation ; then the serum and the sublimate in the dressing 

 having been allowed to act upon each other for about half an hour, a little more 

 serum was poured in, the tube being in the same position as before. The result 

 was that a certain quantity flowed out below, and was received into a test-tube. 

 The lower part of the wool and the serum in the test-tube were next inoculated 

 with putrid blood, diluted with ten parts of water, to prevent the smell being 

 so great as to make one think that putrefaction existed when none had occurred, 

 a tenth of a minim being applied by means of a suitable apparatus. Lastly, 

 the wool-tube in its stoppered bottle, and the test-tube with a cap of thin 

 macintosh tied over its mouth, were replaced in the warm box. The object 

 of this was to ascertain whether the dressing, after having been thoroughly 

 soaked through and through with serum, would resist a potent septic inoculation ; 

 and also whether the fluid that had come through the dressing was itself an 

 antiseptic fluid. If such should prove to be the case, we should have all the 

 requisites we could desire for an antiseptic dressing. It was a very severe test, 

 for it is comparatively rarely that we have such intensely putrefying substances 

 applied to the surface of our surgical dressings, and it is also comparatively 

 rarely that the dressings are soaked so very thoroughly with blood or scrum. 



I used three kinds of sublimate-wool, one containing i per cent. — twice 

 as much as there is in the wood-wool — one 5 per cent., and the other 10 per cent. 

 I have mentioned that it was on the 9th of September that this was done, and 



